This disclosure relates to bypass duct for a gas turbine engine that includes drag links that are angled based on local air flow conditions.
Gas turbine engines have a core airflow that comprises a primary flow through a core engine and a fan airflow that comprises a bypass airflow between an outer surface of the core engine and an inner surface of a nacelle cowling. Air flows into the fan inlet and is split into the primary and bypass airflows by a splitter. The primary flow passes through low and high pressure compressors and generates the pressure required for efficient combustion. The air is then expanded through high and low turbine modules, which extract energy used to power the compressors and fan. The primary air flow leaves the engine through a primary exhaust nozzle and the bypass air flow is discharged through a secondary nozzle. The primary air flow provides approximately 10% of the total forward thrust while the bypass airflow supplies approximately 90% of the total forward thrust. When a thrust reverser is deployed, the secondary nozzle is blocked and bypass air is directed outward in a forward direction and through reverser cascades to provide reverse thrust.
As most of the airflow passes through the bypass duct between the nacelle cowling and engine core, the thrust specific fuel consumption (TSFC) is very sensitive to pressure loss in the bypass duct. One structure that contributes to the pressure loss is thrust reverser drag links. These drag links cause blocker doors to pivot into a flow blocking position when the thrust reverser is deployed during landing. Therefore, it is desired to improve TSFC while at the same time preserving the functionality performed by the drag links of the thrust reverser.